A fluorescent composite material of NH2-ZnS@β-CD-MOF, its preparation method and application

Abstract

This invention provides an NH2-ZnS@β-CD-MOF fluorescent composite material, its preparation method, and its application. Specifically, β-CD-MOF and NH2-ZnS are dissolved in a methanol solution, stirred in the dark, and centrifuged to obtain a white precipitate. The white precipitate is then washed with methanol solution and vacuum dried in the dark to obtain the NH2-ZnS@β-CD-MOF fluorescent composite material. This fluorescent composite material is used in the preparation of fluorescent sensors. The fluorescent sensor of this invention can not only achieve linear detection of formaldehyde at low concentrations but also detect 4-chlorophenol in aqueous solutions. Furthermore, when the concentration of NH2-ZnS@β-CD-MOF is 0.7 mg / mL, the composite material dispersed in deionized water exhibits the highest luminescence intensity and shows good linearity for both formaldehyde and 4-chlorophenol within a certain concentration range.

Description

Technical Field

[0001] This invention belongs to the field of organic pollutant detection technology, and relates to fluorescence sensors, specifically an NH2-ZnS@β-CD-MOF fluorescent composite material, its preparation method, and its application. Background Technology

[0002] Fluorescent sensors are widely used for detecting harmful substances such as formaldehyde and 4-chlorophenol due to their advantages of high selectivity, simple operation, low cost, real-time detection, and short response time. Among these fluorescent sensors, those based on metal-organic frameworks (MOFs) are more attractive in terms of structural features, functional composition, and the interaction between MOFs and analytes. However, the presence of metals such as Cd, Cu, and Zn in MOFs can pose certain environmental hazards. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide an NH2-ZnS@β-CD-MOF fluorescent composite material, its preparation method, and its application, thereby solving the technical problem that the toxicity of MOFs used in existing fluorescent sensors needs to be further reduced.

[0004] Another objective of this invention is to provide an NH2-ZnS@β-CD-MOF fluorescent composite material, its preparation method, and its application, in order to solve the technical problem that the detection limits of formaldehyde and 4-chlorophenol in existing fluorescent sensors need to be further improved.

[0005] To solve the above technical problems, the present invention adopts the following technical solution:

[0006] A method for preparing an NH2-ZnS@β-CD-MOF fluorescent composite material, the method comprising the following steps:

[0007] Step 1, Preparation of β-CD-MOF:

[0008] β-CD (i.e., β-cyclodextrin) and KOH were dissolved in deionized water, sonicated and filtered. Methanol solution was added to the filtrate, sealed and placed at room temperature. After the methanol vapor diffused, white crystals were produced. The white crystals were washed, filtered and vacuum dried to obtain β-CD-MOF.

[0009] Step 2, Preparation of NH2-ZnS:

[0010] Zn(NO3)2·6H2O and CH4N2S were dissolved in a mixture of ethylenediamine and deionized water, stirred, and transferred to a hydrothermal reactor. The mixture was kept at a constant temperature and the reaction was carried out. After the reaction was completed, the mixture was cooled to room temperature to obtain a white precipitate. The precipitate was centrifuged and washed until the supernatant was colorless and transparent. The precipitate was then dried under vacuum to obtain NH2-ZnS.

[0011] Step 3: Preparation of NH2-ZnS@β-CD-MOF fluorescent composite material:

[0012] The β-CD-MOF obtained in step one and the NH2-ZnS obtained in step two were dissolved in methanol solution. After stirring in the dark, the mixture was centrifuged to obtain a white precipitate. The white precipitate was washed with methanol solution and then dried under vacuum in the dark to obtain the NH2-ZnS@β-CD-MOF fluorescent composite material.

[0013] The present invention also has the following technical features:

[0014] In step one, 2.84g of β-CD and 1.12g of KOH are added to every 100mL of deionized water.

[0015] In step two, 0.297g of Zn(NO3)2·6H2O and 0.228g of CH4N2S are dissolved in 50mL of ethylenediamine and stirred for 0.5h. Then, 10mL of deionized water is added and stirring is continued for another 0.5h.

[0016] In step two, the temperature of the hydrothermal reactor is 110℃.

[0017] In step three, the mass ratio of β-CD-MOF obtained in step one to NH2-ZnS obtained in step two is (1-5):1.

[0018] Preferably, in step three, the mass ratio of β-CD-MOF obtained in step one to NH2-ZnS obtained in step two is 4:1.

[0019] In step three, the β-CD-MOF obtained in step one and the NH2-ZnS obtained in step two are dissolved in 20 mL of methanol solution.

[0020] In step three, stir for 6 hours in the dark.

[0021] The present invention also protects an NH2-ZnS@β-CD-MOF fluorescent composite material, which is prepared by the preparation method of the NH2-ZnS@β-CD-MOF fluorescent composite material as described above.

[0022] This invention also protects the application of the NH2-ZnS@β-CD-MOF fluorescent composite material as described above in the preparation of fluorescent sensors.

[0023] The fluorescent sensor described above is used to detect formaldehyde and 4-chlorophenol.

[0024] The concentration of the dispersion of the NH2-ZnS@β-CD-MOF fluorescent composite material in the fluorescent sensor is 0.5 mg / mL to 0.9 mg / mL.

[0025] Preferably, the concentration of the dispersion of the NH2-ZnS@β-CD-MOF fluorescent composite material in the fluorescent sensor is 0.7 mg / mL.

[0026] The dispersion solvent of the NH2-ZnS@β-CD-MOF fluorescent composite material in the fluorescent sensor is N'N-dimethylformamide, methanol, acetone, anhydrous ethanol, acetonitrile, or deionized water.

[0027] Compared with the prior art, the present invention has the following technical effects:

[0028] (I) The fluorescent composite material of the present invention has excellent luminescence properties. The MOF used is β-cyclodextrin (i.e. β-CD). The raw materials are green, safe, inexpensive and readily available. It can not only improve the defects of traditional MOF materials in terms of toxicity, but also effectively reduce the environmental harm of MOF organic matter.

[0029] (II) The fluorescent composite material of the present invention is β-cyclodextrin-MOF composite amino-functionalized quantum dot NH2-ZnS@β-CD-MOF. This material has high yield, unique photoluminescence properties and low toxicity, providing a new idea for the development of fluorescent sensors.

[0030] (III) The fluorescent sensor constructed from the NH2-ZnS@β-CD-MOF fluorescent composite material of the present invention can not only achieve low-concentration linear detection of formaldehyde, but also be used for the detection of 4-chlorophenol in aqueous solution. When the concentration of NH2-ZnS@β-CD-MOF is 0.7 mg / mL, the luminescence intensity of the composite material dispersed in deionized water is the largest, and it can show good linearity for both formaldehyde and 4-chlorophenol within a certain concentration range.

[0031] (IV) The fluorescence sensor constructed from the NH2-ZnS@β-CD-MOF fluorescent composite material of the present invention has a detection limit of 1.6 nmol / L for formaldehyde and a detection limit of 3.3 nmol / L for 4-chlorophenol. Attached Figure Description

[0032] Figure 1(a) shows the FTIR spectrum of the NH2-ZnS@β-CD-MOF fluorescent composite material.

[0033] Figure 1(b) shows the XPS full spectrum of the NH2-ZnS@β-CD-MOF fluorescent composite material.

[0034] Figure 1(c) shows the Zn2p spectrum of the XPS of the NH2-ZnS@β-CD-MOF fluorescent composite material.

[0035] Figure 1(d) shows the S2p spectrum of XPS for the NH2-ZnS@β-CD-MOF fluorescent composite material.

[0036] Figure 1(e) shows the O1s spectrum of XPS for the NH2-ZnS@β-CD-MOF fluorescent composite material.

[0037] Figure 1(f) shows the C1s spectrum of XPS of the NH2-ZnS@β-CD-MOF fluorescent composite material.

[0038] Figure 2 The fluorescence emission intensity spectra of NH2-ZnS, β-CD-MOF and NH2-ZnS@β-CD-MOF at 330 nm are shown.

[0039] Figure 3 The fluorescence spectra of formaldehyde by fluorescence sensors with mass ratios of NH2-ZnS and β-CD-MOF of 1:2, 1:3, 1:4, and 1:5 are shown.

[0040] Figure 4 The fluorescence spectra of 4-chlorophenol are shown for fluorescence sensors with mass ratios of NH2-ZnS and β-CD-MOF of 1:2, 1:3, 1:4, and 1:5.

[0041] Figure 5 The fluorescence spectra of the NH2-ZnS@β-CD-MOF fluorescent composite material with different dispersion concentrations are shown.

[0042] Figure 6 Fluorescence spectrum of the dispersion solvent of the fluorescent sensor constructed from NH2-ZnS@β-CD-MOF fluorescent composite material.

[0043] Figure 7 Fluorescence spectra of formaldehyde (a, b) and 4-chlorophenol (c, d) detected by the fluorescence sensor constructed from NH2-ZnS@β-CD-MOF fluorescent composite material, and the linear relationship between fluorescence intensity and formaldehyde concentration.

[0044] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0045] It should be noted that, unless otherwise specified, all raw materials and instruments used in this invention are those known in the prior art. For example, β-cyclodextrin (i.e., β-CD) is commercially available β-cyclodextrin.

[0046] The specifications of the instruments and raw materials used in this invention are as follows:

[0047] Electronic analytical balance, Shenyang Longteng Electronic Weighing Instruments Co., Ltd.

[0048] Electric heating drying oven, Beijing Kewei Yongxing Instrument Co., Ltd.

[0049] Ultrasonic cleaning machine, Zhejiang Ningbo Instrument Co., Ltd.

[0050] Magnetic heating stirrer, Changzhou Guohua Electric Appliance Co., Ltd.

[0051] Scanning electron microscope, Carl Zeiss Management Ltd.

[0052] Vacuum drying oven, Tianjin Test Instrument Co., Ltd.

[0053] β-Cyclodextrin, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0054] Thiourea, Sinopharm Chemical Reagent Co., Ltd.

[0055] Zinc nitrate hexahydrate, Shanghai Jingchun Biochemical Technology Co., Ltd.

[0056] Potassium hydroxide, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0057] Ethylenediamine, Sinopharm Chemical Reagent Co., Ltd.

[0058] Methanol, Sinopharm Chemical Reagent Co., Ltd.

[0059] Formaldehyde, Xilong Chemical Co., Ltd.

[0060] 4-Chlorophenol, Sinopharm Chemical Reagent Co., Ltd.

[0061] In this invention, cyclodextrin-based metal-organic frameworks (β-CD-MOFs) may be an effective alternative to common MOFs. However, β-CD-MOFs themselves have poor optical signals, limiting their direct use in fluorescence-based measurements. This invention addresses this deficiency by introducing luminescent quantum dots (QDs) into β-CD-MOFs. Zinc sulfide (ZnS) possesses a large exciton binding energy. This invention further functionalizes ZnS, then uses the modified ZnS (i.e., NH2-ZnS) as luminescent quantum dots (QDs). Therefore, the NH2-ZnS@β-CD-MOF fluorescent composite material in this invention is prepared from NH2-ZnS and β-CD-MOF. Fluorescent sensors prepared using the NH2-ZnS@β-CD-MOF fluorescent composite material of this invention can improve the specificity and detection limits of existing fluorescent sensors for pollutants.

[0062] It should be noted that in this invention, the formaldehyde solution is prepared by taking 0.24 mL of 37 wt.% formaldehyde solution and diluting it to volume in a 50 mL volumetric flask, and then taking 5 mL of the solution and diluting it to volume in a 50 mL volumetric flask in sequence to prepare formaldehyde test solutions with concentration gradients of 50 mmol / L, 5 mmol / L, 500 μmol / L, 50 μmol / L, 5 μmol / L, and 0.5 μmol / L.

[0063] In this invention, the 4-chlorophenol solution is prepared by taking 5 mL of 0.05 mol / L 4-chlorophenol solution and diluting it to volume in a 50 mL volumetric flask, and then taking 5 mL of the solution and diluting it to volume in a 50 mL volumetric flask in sequence to prepare 4-chlorophenol test solutions with concentration gradients of 1 mmol / L, 0.1 mmol / L, 10 μmol / L, and 1 μmol / L.

[0064] In this invention, room temperature refers to the ambient temperature during the production process, which is typically within the range of 20±10℃.

[0065] In this invention, the excitation wavelength for fluorescence testing is 300 nm, the slit width is 5 nm, and the gain is 1.

[0066] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0067] Example 1:

[0068] This embodiment provides a method for preparing an NH2-ZnS@β-CD-MOF fluorescent composite material, which includes the following steps:

[0069] Step 1, Preparation of β-CD-MOF:

[0070] Dissolve 2.84 g β-CD and 1.12 g KOH in 100 mL of deionized water and sonicate for 30 min. Filter the sonicated solution through a 0.45 μm filter and transfer the solution to a 250 mL beaker. Add 100 mL of methanol solution and seal the beaker. Let it stand at room temperature for 5–7 days. Collect the white crystals and spin them at 3000 rpm. -1 Centrifuge for 5 min, wash three times with anhydrous ethanol, and vacuum dry at 45℃ for 12 h to obtain β-CD-MOF.

[0071] Step 2, Preparation of NH2-ZnS:

[0072] 0.297 g Zn(NO3)2·6H2O and 0.228 g CH4N2S were dissolved in 50 mL ethylenediamine and stirred for 0.5 h. Then, 10 mL of deionized water was added to the solution, and stirring was continued for another 0.5 h. The mixture was then transferred to a polytetrafluoroethylene reactor and reacted at 110 °C for 24 h. After the reaction was complete, the reactor was cooled to room temperature, and the mixture was then rotated at a speed of 3000 r·min. -1 Centrifuge for 5 min, wash the white precipitate three times with anhydrous ethanol until the supernatant is colorless and transparent, and dry it under vacuum at 60℃ for 12 h to obtain NH2-ZnS.

[0073] Step 3: Preparation of NH2-ZnS@β-CD-MOF fluorescent composite material:

[0074] Weigh 25 mg NH2-ZnS and 100 mg β-CD-MOF, dissolve both raw materials in 20 mL of methanol solution, and stir for 6 h in the dark at a speed of 3000 r·min. -1 Centrifuge for 5 min, discard the supernatant, and wash the white precipitate three times with 5 mL of methanol solution. Dry the centrifuged white precipitate under vacuum at 60 °C for 12 h in the dark to obtain the NH2-ZnS@β-CD-MOF fluorescent composite material.

[0075] Figure 1(a) shows the infrared spectra of β-CD-MOF, NH2-ZnS, and NH2-ZnS@β-CD-MOF fluorescent composites. NH2-ZnS@β-CD-MOF and β-CD-MOF exhibit infrared spectra in the 3500-3000 cm⁻¹ range. -1 The characteristic absorption peaks are similar in position, and the peaks for -OH, CH, and C=O are located at 3300–3500, 2930, and 1654 cm⁻¹, respectively. -1 Between these values, the symmetrical deformation vibration peak of the CO skeleton appears at 1030 cm⁻¹. -1 Left and right. In the NH2-ZnS infrared spectrum, 3242 cm⁻¹ -1 and 1578cm -1 The absorption peak at 2939 cm⁻¹ is attributed to the NH vibration of the primary amine. -1 The peaks at 639 cm⁻¹ represent the CH stretching vibrations of the methylene group. Additionally, the peak at 639 cm⁻¹... -1 The peak at 1651 cm⁻¹ is a typical Zn-S vibrational peak of ZnS, confirming the successful synthesis of NH₂-ZnS. By comparing the infrared spectra of NH₂-ZnS@β-CD-MOF and β-CD-MOF, the Fourier transform infrared peak of NH₂-ZnS@β-CD-MOF is at 1651 cm⁻¹. -1 and 2930cm -1The peak intensity increased at 1026 cm⁻¹, which is related to the NH bending vibration of NH₂-ZnS. Furthermore, the infrared spectrum of the NH₂-ZnS@β-CD-MOF fluorescent composite material showed an increase at 1026 cm⁻¹. -1 and 1654cm -1 The wavelength shifts towards shorter wavelengths, which is attributed to the hydrogen bond interaction between the NH2-ZnS and β-CD-MOF composite materials. These results demonstrate the successful synthesis of the NH2-ZnS@β-CD-MOF fluorescent composite material.

[0076] Figure 1(b) shows the XPS full spectrum of the NH2-ZnS@β-CD-MOF fluorescent composite material; as can be seen from Figure 1(b), NH2-ZnS@β-CD-MOF contains Zn, S, O and C elements.

[0077] From Figure 1(c), it can be seen that the two peaks at 1020.0 and 1044.2 eV in the Zn2p spectrum of NH2-ZnS@β-CDs-MOF correspond to the Zn2p peaks of ZnS, respectively. 3 / 2 and Zn2p 1 / 2 The presence of a spin orbital peak and a characteristic peak difference of 24.2 eV indicates that Zn in ZnS mainly exists as Zn2. 2+ exist.

[0078] In Figure 1(d), the XPS spectrum of S2p shows two characteristic peaks around 161.8 eV. These two peaks, located at 161.8 eV and 159.7 eV respectively, correspond to S2p. 1 / 2 and S2p 3 / 2 Furthermore, the characteristic peak difference is 2.1 eV, therefore, in ZnS, S mainly exists as S0. 2- In the form of.

[0079] The O1s spectrum in Figure 1(e) shows peaks at binding energies of 532.4, 531.5, and 530.7 eV, which correspond to C=O, CO, and surface-adsorbed -OH, respectively.

[0080] The XPS spectra of C1s in Figure 1(f) show binding energy peaks at 286.0 and 284.6 eV, corresponding to CO and C=O, respectively. These results also indicate the successful synthesis of the NH2-ZnS@β-CD-MOF fluorescent composite material.

[0081] Figure 2 The interaction between NH2-ZnS and β-CD-MOF was investigated by analyzing the fluorescence spectra of NH2-ZnS, β-CD-MOF, and NH2-ZnS@β-CD-MOF. Figure 2As shown, when the excitation wavelength is 300 nm, all three materials exhibit a strong emission peak at 330 nm. Compared to β-CD-MOF and NH2-ZnS@β-CD-MOF, NH2-ZnS exhibits higher fluorescence intensity. This is because the abundant NH2 modification creates surface defects on the ZnS surface, which can generate variable energy gaps and enhance the fluorescence intensity of ZnS. β-CD-MOF has the lowest fluorescence intensity because a large amount of β-CD-MOF aggregates in the solution, resulting in low fluorescence intensity. The addition of NH2-ZnS increases the fluorescence intensity because the hydrophobic hydroxyl groups of β-CD-MOF form hydrogen bonds with the amino groups of NH2-ZnS. The formation of hydrogen bonds increases the stability of β-CD-MOF, thereby reducing the energy loss due to non-radiative spin transitions in β-CD-MOF. The above results also indicate that the fluorescence intensity of the NH2-ZnS@β-CD-MOF fluorescent composite material originates from the NH2-ZnS quantum dots, therefore the NH2-ZnS@β-CD-MOF fluorescent composite material can be used to construct fluorescent sensors.

[0082] Examples 2 to 4:

[0083] This embodiment provides a method for preparing NH2-ZnS@β-CD-MOF fluorescent composite material. This method is basically the same as the preparation method in Example 1, except that the ratio of NH2-ZnS to β-CD-MOF is different in step three. In this embodiment, the mass ratio of NH2-ZnS to β-CD-MOF is 1:2, 1:3 and 1:5, respectively.

[0084] Example 5: (Different mass ratios)

[0085] This example illustrates the application of the NH2-ZnS@β-CD-MOF fluorescent composite material in the fabrication of a fluorescent sensor. The fluorescent sensor is used to detect formaldehyde and 4-chlorophenol.

[0086] This embodiment tested the effect of different mass ratios of NH2-ZnS and β-CD-MOF (NH2-ZnS to β-CD-MOF mass ratios of 1:2, 1:3, 1:4, and 1:5) on a fluorescent sensor constructed from the NH2-ZnS@β-CD-MOF fluorescent composite material. This embodiment also provides the application conditions, linear concentration range, and detection limit for formaldehyde and 4-chlorophenol using the fluorescent sensor constructed from the NH2-ZnS@β-CD-MOF fluorescent composite material.

[0087] In this embodiment, the preparation process of the fluorescent sensor constructed from NH2-ZnS@β-CD-MOF fluorescent composite material is as follows: 7 mg of NH2-ZnS@β-CD-MOF fluorescent composite material powder is weighed and dissolved in 10 mL of deionized water, and ultrasonically dispersed for 30 min to form a uniformly dispersed suspension. 2 mL of the above dispersion is measured into a cuvette to obtain the fluorescent sensor constructed from NH2-ZnS@β-CD-MOF fluorescent composite material.

[0088] The analysis of formaldehyde by the fluorescent sensor constructed from NH2-ZnS@β-CD-MOF fluorescent composite material mainly depends on the luminescence intensity of the NH2-ZnS@β-CD-MOF fluorescent composite material. The change in fluorescence intensity is mainly related to the synthesis ratio of NH2-ZnS and β-CD-MOF composite material.

[0089] like Figure 3 As shown in the figure, four sets of experiments were designed for formaldehyde detection at ratios of 1:2, 1:3, 1:4, and 1:5. The figure shows that as the ratio of NH2-ZnS to β-CD-MOF increases from 1:2 to 1:5, the fluorescence intensity of NH2-ZnS@β-CD-MOF first increases and then decreases with increasing β-CD-MOF mass, reaching its maximum at a mass ratio of 1:4. These results indicate that a mass ratio of 1:4 for NH2-ZnS to β-CD-MOF is the optimal ratio for formaldehyde detection in the fluorescent sensor constructed from the NH2-ZnS@β-CD-MOF fluorescent composite material.

[0090] Figure 4 The fluorescence intensity spectra of NH2-ZnS@β-CD-MOF fluorescent composite materials with different mass ratios of NH2-ZnS and β-CD-MOF were obtained for use as a fluorescent sensor for 4-chlorophenol. Figure 4 As can be seen, when the ratio of NH2-ZnS to β-CD-MOF increases from 1:2 to 1:5, the fluorescence intensity of NH2-ZnS@β-CD-MOF first increases and then decreases with the increase of β-CD-MOF mass. The fluorescence intensity reaches its maximum when the molar ratio is 1:4, because NH2-ZnS is the main luminescent source of the composite material. When the mass of NH2-ZnS is too large, the fluorescence intensity decreases, possibly because a large amount of NH2-ZnS aggregates, causing some energy to transition via non-radiative energy transitions, thus reducing the fluorescence intensity. The fluorescence spectrum shows that a mass ratio of NH2-ZnS to β-CD-MOF of 1:4 is the optimal ratio for detecting 4-chlorophenol using the NH2-ZnS@β-CD-MOF fluorescent composite material.

[0091] Example 6: (Different dispersion concentrations)

[0092] This embodiment illustrates the application of the NH2-ZnS@β-CD-MOF fluorescent composite material (i.e., the mass ratio of NH2-ZnS to β-CD-MOF is 1:4) from Example 1 in the fabrication of a fluorescent sensor. The fluorescent sensor is used to detect formaldehyde and 4-chlorophenol.

[0093] In this embodiment, the preparation process of the fluorescent sensor constructed from the NH2-ZnS@β-CD-MOF fluorescent composite material is basically the same as that in Example 5. The only difference is that in this embodiment, 5 mg, 6 mg, 7 mg, 8 mg and 9 mg of NH2-ZnS@β-CD-MOF fluorescent composite material powder are weighed in sequence and dissolved in 10 mL of deionized water.

[0094] To achieve optimal fluorescence detection performance of the fluorescent sensor constructed from NH2-ZnS@β-CD-MOF fluorescent composite material for formaldehyde and 4-chlorophenol, the fluorescence experimental conditions of the NH2-ZnS@β-CD-MOF fluorescent composite material were optimized. Different masses of NH2-ZnS@β-CD-MOF fluorescent composite material (5 mg, 6 mg, 7 mg, 8 mg, and 9 mg) were weighed and ultrasonically dispersed in 10 mL of deionized water for 20 min. Figure 5 As shown, the fluorescence intensity increases with increasing concentration of the NH2-ZnS@β-CD-MOF dispersion, reaching its maximum at a concentration of 0.7 mg / mL. Further increasing the NH2-ZnS@β-CD-MOF concentration leads to a decrease in fluorescence intensity, likely due to the aggregation of a large amount of fluorescent material, causing fluorescence to transition in a non-radiative manner, consuming some energy and thus reducing intensity. These results indicate that 0.7 mg / mL is the optimal concentration for the fluorescence sensor.

[0095] Example 7: (Different dispersion solvents)

[0096] This embodiment illustrates the application of the NH2-ZnS@β-CD-MOF fluorescent composite material (i.e., the mass ratio of NH2-ZnS to β-CD-MOF is 1:4) from Example 1 in the fabrication of a fluorescent sensor.

[0097] In this embodiment, the preparation process of the fluorescent sensor constructed from the NH2-ZnS@β-CD-MOF fluorescent composite material is basically the same as that in Example 5. The only difference is that in this embodiment, the dispersion solvents examined are N'N-dimethylformamide, methanol, acetone, anhydrous ethanol, acetonitrile, or deionized water.

[0098] Since the dispersion solvent system has a significant impact on the detection of the fluorescence sensor, several commonly used solutions were selected as research objects. In this embodiment, the effect of the dispersion solvent of the fluorescence sensor on the fluorescence intensity of NH2-ZnS@β-CD-MOF was investigated at an excitation wavelength of 300 nm. Figure 6 It can be seen that the fluorescence intensity of the sensor varies depending on the dispersion solvent of the NH2-ZnS@β-CD-MOF fluorescent composite material, indicating a correlation with the polarity of the dispersion solvent. The figure shows that the NH2-ZnS@β-CD-MOF fluorescent composite material exhibits the highest fluorescence intensity when dispersed in deionized water, and the lowest fluorescence intensity when dispersed in acetone. This is because the polarity of deionized water is much greater than that of acetonitrile, DMF, and methanol, and its fluorescence intensity changes with the dispersion solvent. This demonstrates that the fluorescence intensity is consistent with the polarity of the dispersion solvent. These results indicate that the polarity of the dispersion solvent affects the fluorescence intensity of the fluorescence sensor, and that polarity is positively correlated with fluorescence intensity.

[0099] Example 8: (Examining the detection limit)

[0100] This embodiment illustrates the application of the NH2-ZnS@β-CD-MOF fluorescent composite material (i.e., the mass ratio of NH2-ZnS to β-CD-MOF is 1:4) from Example 1 in the fabrication of a fluorescent sensor. The fluorescent sensor is used to detect formaldehyde and 4-chlorophenol.

[0101] In this embodiment, the preparation process of the fluorescent sensor constructed from the NH2-ZnS@β-CD-MOF fluorescent composite material is the same as that in Example 5.

[0102] The fluorescence sensor constructed from the NH2-ZnS@β-CD-MOF fluorescent composite material prepared in this embodiment exhibits fluorescence spectra for formaldehyde and 4-chlorophenol, as well as a linear relationship between fluorescence intensity and formaldehyde concentration, as shown in the figure. Figure 7 As shown.

[0103] Figure 7 Image (a) shows the fluorescence intensity at 330 nm of the fluorescence sensor constructed from the NH2-ZnS@β-CD-MOF fluorescent composite material as a function of formaldehyde concentration. The fluorescence intensity gradually increases with increasing formaldehyde concentration. Furthermore, Figure 7 (b) indicates that the formaldehyde concentration is 5.0 × 10⁻⁶. -3 Within the concentration range of μmol / L to 1.0 μmol / L, the fluorescence signal changes with increasing concentration, and this linear equation can be expressed as: F = 2087lgC(μmol / L) + 6327, (R 2=0.995), thus the detection limit of the fluorescent sensor constructed from NH2-ZnS@β-CD-MOF fluorescent composite material is calculated to be 1.6 nmol / L.

[0104] Figure 7 (c) shows the quantitative analysis of 4-chlorophenol by a fluorescent sensor constructed from NH2-ZnS@β-CD-MOF fluorescent composite material. The figure shows that when the concentration of 4-chlorophenol is 1.0 × 10⁻⁶... -2 Within the range of μmol / L to 10 μmol / L, the fluorescence intensity increased with increasing 4-chlorophenol concentration; Figure 7 From (d), we can see that the linear equation for the change in fluorescence intensity with the concentration of 4-chlorophenol is: F = 1175lgC(μmol / L) + 3896(R) 2 =0.994), thus the detection limit of the fluorescent sensor constructed from NH2-ZnS@β-CD-MOF fluorescent composite material for 4-chlorophenol was calculated to be 3.3 nmol / L.

[0105] The above results indicate that the fluorescent sensor constructed from the NH2-ZnS@β-CD-MOF fluorescent composite material holds promise for detecting the two pollutants mentioned above. This is because β-CD-MOF possesses a unique three-dimensional cyclic structure and a fixed internal cavity size, allowing small molecules of FA and 4-CP to enter the cavity and react with the electron-rich functional groups of NH2-ZnS, thus achieving sensitive detection of formaldehyde and 4-chlorophenol.

Claims

1. A method for preparing NH2-ZnS@β-CD-MOF fluorescent composite material, characterized in that, The method comprises the following steps: Step one, preparation of β-CD-MOF: Dissolve β-CD and KOH in deionized water, ultrasonic and filter, add methanol solution in the filtrate, seal and place at room temperature, after the methanol vapor diffuses, white crystals are produced, wash and filter the white crystals, and vacuum dry to prepare β-CD-MOF; the β-CD is β-cyclodextrin; Step two, preparation of NH2-ZnS: Dissolve Zn(NO3)2·6H2O and CH4N2S in a mixture of ethylenediamine and deionized water, stir and transfer to a hydrothermal reactor, keep warm to react, cool to room temperature after the reaction is completed, centrifugal wash until the supernatant is colorless and transparent, and vacuum dry to prepare NH2-ZnS; Step three, preparation of NH2-ZnS@β-CD-MOF fluorescent composite material: Dissolve β-CD-MOF obtained in step one and NH2-ZnS obtained in step two in methanol solution, the mass ratio of β-CD-MOF obtained in step one and NH2-ZnS obtained in step two is (1-5):1; centrifugal the white precipitate obtained after stirring in the dark, wash the white precipitate with methanol solution, and vacuum dry the washed white precipitate in the dark to prepare NH2-ZnS@β-CD-MOF fluorescent composite material.

2. The preparation method of NH2-ZnS@β-CD-MOF fluorescent composite material according to claim 1, characterized in that, In step one, 2.84g of β-CD and 1.12g of KOH are added in 100mL of deionized water.

3. The preparation method of NH2-ZnS@β-CD-MOF fluorescent composite material according to claim 1, characterized in that, In step two, 0.297 g of and 0.228 g of CH4N2S were dissolved in 50 mL of ethylenediamine and stirred for 0.5 h, 10 mL of deionized water was added and stirring was continued for 0.5 h. In step two, the temperature of the hydrothermal reactor is 110℃.

4. The preparation method of NH2-ZnS@β-CD-MOF fluorescent composite material according to claim 1, characterized in that, In step three, β-CD-MOF obtained in step one and NH2-ZnS obtained in step two are dissolved in 20mL of methanol solution; In step three, stir for 6h in the dark.

5. A NH2-ZnS@β-CD-MOF fluorescent composite material, characterized in that, The fluorescent composite material is prepared by the preparation method of NH2-ZnS@β-CD-MOF fluorescent composite material in any one of claims 1 to 4.

6. Application of NH2-ZnS@β-CD-MOF fluorescent composite material in claim 5 to prepare a fluorescent sensor.

7. Use according to claim 6, wherein The fluorescent sensor is used to detect formaldehyde or 4-chlorophenol.

8. The use according to claim 6, wherein the compound is ###00003### or a pharmaceutically acceptable salt thereof. The dispersion concentration of NH2-ZnS@β-CD-MOF fluorescent composite material in the fluorescent sensor is 0.5mg / mL-0.9mg / mL.

9. Use according to claim 8, wherein the compound is ###0002### The dispersion concentration of NH2-ZnS@β-CD-MOF fluorescent composite material in the fluorescent sensor is 0.7mg / mL.

10. The use according to claim 6, wherein The dispersion solvent of NH2-ZnS@β-CD-MOF fluorescent composite material in the fluorescent sensor is N’N-dimethylformamide, methanol, acetone, anhydrous ethanol, acetonitrile or deionized water.

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